Cleaning compositions in solid form, such as tablet form, are known in the art (e.g., see U.S. Pat. No. 4,099,912 (Ehrlich), U.S. Pat. No. 4,642,197 (Kruse et al.), U.S. Pat. No. 4,654,341 (Nelson et al.), U.S. Pat. No. 4,897,212 (Kruse et al.), U.S. Pat. No. 5,225,100 (Fry et al.), U.S. Pat. No. 5,756,440 (Watanabe et al.), U.S. Pat. No. 5,858,959 (Surutzidis et al.), U.S. Pat. No. 6,664,226 (Jacques et al.), U.S. Pat. No. 6,689,305 (Fernholz et al.), U.S. Pat. No. 7,153,817 (Binder), U.S. Pat. No. 7,598,217 (Burg et al.), U.S. Pat. No. 8,357,647 (Sharma et al.), and U.S. Pat. No. 8,426,350 (Geret et al.) and U.S. Pat. App. Pub. Nos. US2003/0100101 (Huth et al.), US2003/0171245 (Goovaerts et al.), US2005/0113279 (Desmarescaux et al.), US2011/0118166 (Tjelta et al.), US2012/0142576 (Bartelme et al.), and US2013/0109609 (Smith et al.)). Tablets provide individual doses of cleaning compositions. Many consumers find tablet forms of cleaning compositions to be more convenient and in some applications more attractive than traditional liquid or powder forms. Tablets are more compact, and thus facilitate transport and storage. Tablets also eliminate the need for measuring, resulting in precise dosing and avoiding wasteful overdosing or underdosing. Tablets also make the compositions easier to handle and dispense. For these reasons, cleaning products in tablet form have become very popular.
Tablet binders are compounds used to bind together the ingredients and hold together the structure of the tablets. Conventional binders used in the formation of tablets of cleaning compositions have been found wanting in several respects. Some binders exhibit undesirable friable properties when subjected to high compression, thus causing difficulties in packaging and shipping as well as increasing costs due to losses of uniform tablet size and decreased aesthetic appeal. Other binders result in tablet compositions characterized as having a low rate of dissolution or result in solutions that are hazy or opaque or that leave a residue upon drying.
Among the conventional tablet binders are borates, such as boric acid, sodium tetraborate decahydrate and sodium perborate. The borate compounds have been used extensively in making a multitude of cleaning, disinfecting, and personal care compositions.
Traditionally, boric acid has been used in tablet compositions because of its ability to act as both a tablet binder and a mold release lubricant. Boric acid also is a very inexpensive material. Boric acid is easy to use in production because it simply needs to be dry mixed into the final tablet composition. Boric acid also is completely soluble in water, which is an important feature when producing products like glass cleaners and detergents. Borates, however, are increasingly becoming a concern for environmental and human health and safety. Borates have a potential to pollute waterways and ground soil if not used and disposed of properly. Due to these concerns, many companies are opting to remove borates completely from their formulations. The complete removal of borates from these compositions presents a challenge to the tablet industry.
Zeolites, which include crystalline aluminum silicates, also have been used as binders for tablets, particularly for detergent compositions, where they can serve a dual function as binder and builder. A problem with using zeolites as tablet binder is that solutions resulting from the dissolved tablets often exhibit a haze or cloudy solution, which for many cleaning compositions is deemed to be unsatisfactory. The solutions when dried also can result in a hazy surface.
Accordingly, a need exists for tablet binding compositions that allow tablet formation without the use of traditional binders, such as borates and zeolites. In addition, a need exists for a tablet binding composition that results in a tablet that is resistant to crumbling or powdering during manufacturing, packaging and shipping processes.